Voltage control



July 24, 1934. I H, C. GRANT, JR 1,967,303

VOLTAGE CONTROL Filed Feb. 2, 1928 m P nunnunl z to'um'uo uouumvuu AL MZE T MM Patented July 24, 1934 assignor to Walter 'Kidde & Company, Inc.,' I New York, N. Y., a corporation of New York Application February'z, 1928, Serial No. 251,322

Claims. (01. 175-363) This invention relates to devices for maintaining a constant voltage supply for operating apparatus which is sensitive to changes in voltage or difference of potential and requires a current sup- "'51 ply of constant voltage for its correct operation. Where such a device isdesigned to function upon changes in voltage or difference of potential, it is very necessary that the current supplied to it normally be at constant voltage, and the present iniidl vention resides in a device formaintaining such constant voltage regardless of fluctuations of voltage inthe source of current. 1

' Inthe copending application Ser. No. 251,321 filed February 2, 1928, there is described a method '13. for maintaining a. constant voltage which utilizes a negative bias on the grid of a three-element vacuum tube varying inproportion to the variations of the plate voltage. In this manner, the changes in the voltage of each element counteract each other and a constant voltage in the output results. The present invention is based upon the same fundamental principle oi-utilizingthe variations of two currents taken from a common varying'source to neutralize each other,- thereby producing a constant output, but uses potentials of diiferent magnitudes upon resistance elements to produce a currentof unvarying characteristics.

An object of this invention, therefore, is to produce an output current of constant voltage by rectifying an alternating input current of varying voltage, impressing the rectified current across a resistance, and applying a second rectified current, difiering in magnitude fromthe first, across a portion of the resistance, thGSECOIld rectified current varying in proportion to the variations in the first rectified current.

' Other objects will be apparent as the invention is described in greater detail and reference will now be had to the accompanying drawing,

#540 wherein:

Figured is a conventional illustration of the circuits required for one embodiment of the invention.

Figure 2 is aconventional illustration of another: embodiment of the invention wherein :greater capacityfor adjustment is provided.

Figure 3 is a conventional illustration of an embodiment .similar to that shown in Figure 2, but showing an arrangement of circuits which utilizes full-wave rectification.

Referring particularly to Figure 1, the primary P of a suitable transformer is connected across a source of power having a voltage EL. S1 and S2 are secondaries of the transformer, the former being connected to the plate of a two-element thermionic valve V1 by wire '01. The filament of this tube is heated by means of a battery D through a variable resistance r. The filament of tube V1 is connected to a resistance R by a wire 02 and the other terminal of the resistance R is connected to the secondary S1 through wire 03. In like manner, the two-element thermionic valve V2 is connected to the secondary S2 by a wire 04, and the filament is heated by battery D1 connected through a variable resistance 11. The filament of the tube V2 is connected through wire 115 with a variable contact R1 on the resistance ele: ment R. Wire vs connects the secondary S2 with wire vs at point 0. The voltage ER across terminals U, U which are connected respectively with the variable contact R1 and the point T is the. output voltage regulated to maintain a constant value. I q 1 Y I An unregulated varying voltage is applied across the primary P of the transformer. The secondaries S1 and S2 joined at the point 0 are connected to the respective thermionic valves V1 and V2, the outputs of each of the secondaries being separately rectified by the respective thermionic valves which act as half-wave rectifiers. The voltage of the secondary S1 is applied through the tube V1 across the resistance R from which any intermediate voltage ER may be tapped. v

As an initial consideration, the ratios of 'the secondaries to the primary are first selected to give the desired voltages, or outputs.

The output of the secondary S2 is made to pass through a portion of the resistance R, represented as that portion between the contact R1 and point 0. For the connections shown, the value of the current from secondary S2 must always greatly exceed, or dominate that from secondary S1. In this manner, there will be a difierential which will be a measure of the output curthe secondary S1, the voltage ER, will remain con stant regardless of voltage changes in the unregulated input voltage EL- If the voltage E1. rises, the potentials at points T and R1 both rise proportionately, causing the difference in potential or voltage between the points R1 and T UNITED STATES PATENT OFFICE:

to remain unchanged. The reverse action 00- curs upon a drop in the input voltage.

In the embodiment of the invention shown in Figure 2, the resistances are apportioned in the respective circuits to afford a greater degree of adjustability. Instead of a single resistance R as in Figure 1, two resistances R2 and R3 are provided. Secondaries S1 and S2 are connected together at O and the plates of the thermionic valves V1 and V2 are connected to the respective secondaries by wires 121 and oi as in Figure 1. The filament of the tube V1 is connected to resistance R2 by wire or. The point of connection with this resistance is indicated at T. ..Wire '03 connects the filament of tube V2 with a resistance R4, the variable contact of which is con--' nected to the resistance R2 by wirevs. The point of connection of 09 with the resistance is indicated at S. Resistance Rz is connected between points 0 and S and is ofv an adjustable character as clearly shown. It will'be seenthat the output of the secondary S2 is impressedacross resistance R2 after passing through the resistance R4. The output of the secondary'S1 is impressed across the same resistance R3 after passing through the resistance R2. By an initial adjustment of the resistances R3 and R4 with respect to the resistance R2, and by the proper adjustment or" the output of the secondary S2 relative to that of secondary S1, the voltage across the resistance R2 will remain constant regardless of changes in the input voltage EL.

The resistance R2 is shown as provided with variable taps for obtaining a plurality of voltages. As explained in connection with the voltage ER of the device shown in Figure .1, the voltage ER across a desired portion of theresistance R2 in Figure 2 will remain constant regardless of changes in the input voltage. If the voltage across the primary P rises, the potential at pointT also rises. Simultaneous with the above rise in potential, the potential at point S rises by reason of the increase in the voltage oi? the secondary S2. By the adjustment described above, the rise and fall of the potentials at points T and S may be made such that the difference of potential, or voltage ER, across these points, will remain constant. This is the condition striven for.

Figure 3 indicates a system similar to that shown in Figure 2 but using full-wave rectifica tion. The secondaries S1 and S2 of the transformer indicated in Figure 2 are, in the system shown in Figure 3, divided into two sections S3, S4 and S5, S6, respectively. In place of the single thermionic valve for each secondary, valves V11 and V12, connected to the secondaries S3, S4, and valves V13 and V14 connected to the secondaries S5, S6 are provided. The filaments of these valves are heated in the same manner as those shown in Figure 2 and the plates thereof are connected to the transformers in such manner that fullwave rectification of the output of each transformer secondary will be had. The midpoints of the two secondaries are connected together at O and the filaments of the tubes V11 and V12 are connected to the resistance R2 by wire or in a manner similar to that in which the filament of the tube V1 is connected to this resistance in Figure 2. In like manner the filaments of valves V12 and V14 are connected to resistance R4 by wire 02. It will be'apparent that the output of the secondaries S5 and S6 is impressed across the in potential across the resistance R2 remains constant for varying values of input voltage EL as described in connection with the circuits shown in Figure 2. The regulated voltage supply ER is available after proper adjustment of the resistances R3 and R4 and the outputs of the respective secondaries.

It will be apparent that the invention may be applied to either alternating or direct current supplies.- The specific apparatus used to accomplish the rectification of the current may be varied to suit individual requirements and the invention is not to be limited save as defined in the'appended claims.

. I claim as my invention:

1. The method of maintaining a constant output current which comprises supplying from a given input current of varying voltage, a varying voltage across a resistance, applying a second voltage across a portion only of the resistance, the second'voltage varying proportionately with the variations of the first, and obtaining from that portion of the resistance not subjected to the'second voltage an output of constant voltage. 2. The method of maintaining a constant output current which comprises supplying, from a. given input current of varying voltage, a varying voltage across a resistance, applying a second independent voltage from the input current across a portion only of the resistance, the second volt age varying proportionately with the variations of the first, and obtaining from that portion of the resistance not subjected to the second voltage an output of constant voltage.

3. Means for maintaining a constant output current comprising an input current of varying voltage, means to obtain from the input two ourrents having voltages which vary in proportion rents having voltages which vary in proportion to each other, a resistance, means for impressing one varying voltage across the resistance, means for impressing the other voltage. across a portion only of the resistance, means to vary the resistance, and means to supply power from the portion of the resistance not subject to the second voltage. 1

5. Means for maintaining a constant output current comprising an input current of varying voltage, means to obtain from the input two currents having voltageswhich vary in proportion to each other, a resistance, one portion thereof being subject to a controlling voltage, means to apply the voltage of oneof the currents across the resistance, means to apply the voltage of the othercurrent across the said portion of the resistance for controlling the voltage across the other portion, means to adjust the current flowing through the first portion, and means to supply power from the second portion of resistance, whereby-the voltage of said power supply will be maintained constant.

6. Means for maintaining a constant output current comprising an input current of varying voltage, means to transform the input to two independent currents having voltages varying proportionately, means to rectify the currents independently, a resistance, means for impressing the voltage of one of the rectified currents across the resistance, means for impressing the voltage of the other rectified current across a portion of the resistance for controlling the voltage across the remainder of the resistance, means for adjusting the second voltage, and means for supplying power from the second portion of the resistance.

'7. Means for maintaining a constant output current comprising an input current of varying voltage, a transformer having two secondary windings, means to impress the input across the primary winding, means to connect the secondary windings together at the points of zero potential, thermionic valves, means to connect the plates of the valves to the other terminals of the secondaries, a resistance, means to connect one terminal thereof to the connection between the windings, means to connect the other resistance terminal to the filament of one of the valves, means to connect the filament of the other valve to an intermediate resistance point, and means to supply power from that portion of the resistance between the second resistance terminal and the intermediate point.

8. Means for maintaining a constant output current comprising an input current of varying voltage, a transformer having two secondary windings, means to impress the input across the primary winding, means to connect the secondary windings together at the points of zero potential, thermionic valves, means to connect the plates of the valves to the other terminals of the secondaries, a resistance, means to connect one terminal thereof to the connection between the windings, means to connect the other resistance terminal to the filament of one of the valves, means to connect the filament of the other valve to an intermediate resistance point, through a variable connection, and means to supply power from that portion of the resistance between the second resistance terminal and the intermediate point.

9. Means for maintaining a constant output current from an input current of varying voltage comprising means to obtain from the input two currents having voltages which vary in proportion to each other, first and second terminals having an electrically conductive path therebetween, a third terminal in said path between the first and second terminals, means for impressing one varying voltage across the first and second terminals so that the second terminal is of a higher potential with respect to a common point of measurement than the first terminal, means for impressing the other voltage across the first and third terminals so that the third terminal is of a higher potential than the first terminal, and means to supply power of constant output from the portion of said electrically conductive path between the second and third terminals.

10. Means for maintaining a constant unidirectional output current comprising an alternating input current of varying voltage, means to convert said input current to uni-directional current, means for impressing said uni-directional current across a plurality of terminals, a vacuum tube and circuit for obtaining a second independent current of varying voltage from the input, and means for applying to one of the terminals relative to the other a voltage which varies proportionately to that of the Voltage across the terminals whereby the difference in potential across the terminals will remain constant.

HARRY CAMPBELL GRANT, JR. 

